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# QVector4D Class Reference

The QVector4D class represents a vector or vertex in 4D space. More...

     #include <QVector4D>

This class was introduced in Qt 4.6.

- List of all members, including inherited members

## Public Functions

| QVector4D ()
| QVector4D ( qreal xpos, qreal ypos, qreal zpos, qreal wpos )
| QVector4D ( const QPoint & point )
| QVector4D ( const QPointF & point )
| QVector4D ( const QVector2D & vector )
| QVector4D ( const QVector2D & vector, qreal zpos, qreal wpos )
| QVector4D ( const QVector3D & vector )
| QVector4D ( const QVector3D & vector, qreal wpos )
bool | isNull () const
qreal | length () const
qreal | lengthSquared () const
void | normalize ()
QVector4D | normalized () const
void | setW ( qreal w )
void | setX ( qreal x )
void | setY ( qreal y )
void | setZ ( qreal z )
QPoint | toPoint () const
QPointF | toPointF () const
QVector2D | toVector2D () const
QVector2D | toVector2DAffine () const
QVector3D | toVector3D () const
QVector3D | toVector3DAffine () const
qreal | w () const
qreal | x () const
qreal | y () const
qreal | z () const
| operator QVariant () const
QVector4D & | operator*= ( qreal factor )
QVector4D & | operator*= ( const QVector4D & vector )
QVector4D & | operator+= ( const QVector4D & vector )
QVector4D & | operator-= ( const QVector4D & vector )
QVector4D & | operator/= ( qreal divisor )

## Static Public Members

qreal | dotProduct ( const QVector4D & v1, const QVector4D & v2 )

## Related Non-Members

bool | qFuzzyCompare ( const QVector4D & v1, const QVector4D & v2 )
bool | operator!= ( const QVector4D & v1, const QVector4D & v2 )
const QVector4D | operator* ( qreal factor, const QVector4D & vector )
const QVector4D | operator* ( const QVector4D & vector, qreal factor )
const QVector4D | operator* ( const QVector4D & v1, const QVector4D & v2 )
const QVector4D | operator+ ( const QVector4D & v1, const QVector4D & v2 )
const QVector4D | operator- ( const QVector4D & v1, const QVector4D & v2 )
const QVector4D | operator- ( const QVector4D & vector )
const QVector4D | operator/ ( const QVector4D & vector, qreal divisor )
QDataStream & | operator<< ( QDataStream & stream, const QVector4D & vector )
bool | operator== ( const QVector4D & v1, const QVector4D & v2 )
QDataStream & | operator>> ( QDataStream & stream, QVector4D & vector )

## Detailed Description

The QVector4D class represents a vector or vertex in 4D space.

The QVector4D class can also be used to represent vertices in 4D space. We therefore do not need to provide a separate vertex class.

Note: By design values in the QVector4D instance are stored as `float`. This means that on platforms where the `qreal` arguments to QVector4D functions are represented by `double` values, it is possible to lose precision.

See also QQuaternion, QVector2D, and QVector3D.

## Member Function Documentation

### QVector4D::QVector4D ()

Constructs a null vector, i.e. with coordinates (0, 0, 0, 0).

### QVector4D::QVector4D ( qreal xpos, qreal ypos, qreal zpos, qreal wpos )

Constructs a vector with coordinates (xpos, ypos, zpos, wpos).

### QVector4D::QVector4D ( const QPoint & point )

Constructs a vector with x and y coordinates from a 2D point, and z and w coordinates of 0.

### QVector4D::QVector4D ( const QPointF & point )

Constructs a vector with x and y coordinates from a 2D point, and z and w coordinates of 0.

### QVector4D::QVector4D ( const QVector2D & vector )

Constructs a 4D vector from the specified 2D vector. The z and w coordinates are set to zero.

See also toVector2D().

### QVector4D::QVector4D ( const QVector2D & vector, qreal zpos, qreal wpos )

Constructs a 4D vector from the specified 2D vector. The z and w coordinates are set to zpos and wpos respectively.

See also toVector2D().

### QVector4D::QVector4D ( const QVector3D & vector )

Constructs a 4D vector from the specified 3D vector. The w coordinate is set to zero.

See also toVector3D().

### QVector4D::QVector4D ( const QVector3D & vector, qreal wpos )

Constructs a 4D vector from the specified 3D vector. The w coordinate is set to wpos.

See also toVector3D().

### qreal QVector4D::dotProduct ( const QVector4D & v1, const QVector4D & v2 )`[static]`

Returns the dot product of v1 and v2.

### bool QVector4D::isNull () const

Returns true if the x, y, z, and w coordinates are set to 0.0, otherwise returns false.

### qreal QVector4D::length () const

Returns the length of the vector from the origin.

See also lengthSquared() and normalized().

### qreal QVector4D::lengthSquared () const

Returns the squared length of the vector from the origin. This is equivalent to the dot product of the vector with itself.

See also length() and dotProduct().

### void QVector4D::normalize ()

Normalizes the currect vector in place. Nothing happens if this vector is a null vector or the length of the vector is very close to 1.

See also length() and normalized().

### QVector4D QVector4D::normalized () const

Returns the normalized unit vector form of this vector.

If this vector is null, then a null vector is returned. If the length of the vector is very close to 1, then the vector will be returned as-is. Otherwise the normalized form of the vector of length 1 will be returned.

See also length() and normalize().

### void QVector4D::setW ( qreal w )

Sets the w coordinate of this point to the given w coordinate.

See also w(), setX(), setY(), and setZ().

### void QVector4D::setX ( qreal x )

Sets the x coordinate of this point to the given x coordinate.

See also x(), setY(), setZ(), and setW().

### void QVector4D::setY ( qreal y )

Sets the y coordinate of this point to the given y coordinate.

See also y(), setX(), setZ(), and setW().

### void QVector4D::setZ ( qreal z )

Sets the z coordinate of this point to the given z coordinate.

See also z(), setX(), setY(), and setW().

### QPoint QVector4D::toPoint () const

Returns the QPoint form of this 4D vector. The z and w coordinates are dropped.

See also toPointF() and toVector2D().

### QPointF QVector4D::toPointF () const

Returns the QPointF form of this 4D vector. The z and w coordinates are dropped.

See also toPoint() and toVector2D().

### QVector2D QVector4D::toVector2D () const

Returns the 2D vector form of this 4D vector, dropping the z and w coordinates.

See also toVector2DAffine(), toVector3D(), and toPoint().

### QVector2D QVector4D::toVector2DAffine () const

Returns the 2D vector form of this 4D vector, dividing the x and y coordinates by the w coordinate and dropping the z coordinate. Returns a null vector if w is zero.

See also toVector2D(), toVector3DAffine(), and toPoint().

### QVector3D QVector4D::toVector3D () const

Returns the 3D vector form of this 4D vector, dropping the w coordinate.

See also toVector3DAffine(), toVector2D(), and toPoint().

### QVector3D QVector4D::toVector3DAffine () const

Returns the 3D vector form of this 4D vector, dividing the x, y, and z coordinates by the w coordinate. Returns a null vector if w is zero.

See also toVector3D(), toVector2DAffine(), and toPoint().

### qreal QVector4D::w () const

Returns the w coordinate of this point.

See also setW(), x(), y(), and z().

### qreal QVector4D::x () const

Returns the x coordinate of this point.

See also setX(), y(), z(), and w().

### qreal QVector4D::y () const

Returns the y coordinate of this point.

See also setY(), x(), z(), and w().

### qreal QVector4D::z () const

Returns the z coordinate of this point.

See also setZ(), x(), y(), and w().

### QVector4D::operator QVariant () const

Returns the 4D vector as a QVariant.

### QVector4D & QVector4D::operator*= ( qreal factor )

Multiplies this vector's coordinates by the given factor, and returns a reference to this vector.

See also operator/=().

### QVector4D & QVector4D::operator*= ( const QVector4D & vector )

Multiplies the components of this vector by the corresponding components in vector.

### QVector4D & QVector4D::operator+= ( const QVector4D & vector )

Adds the given vector to this vector and returns a reference to this vector.

See also operator-=().

### QVector4D & QVector4D::operator-= ( const QVector4D & vector )

Subtracts the given vector from this vector and returns a reference to this vector.

See also operator+=().

### QVector4D & QVector4D::operator/= ( qreal divisor )

Divides this vector's coordinates by the given divisor, and returns a reference to this vector.

See also operator*=().

## Related Non-Members

### bool qFuzzyCompare ( const QVector4D & v1, const QVector4D & v2 )

Returns true if v1 and v2 are equal, allowing for a small fuzziness factor for floating-point comparisons; false otherwise.

### bool operator!= ( const QVector4D & v1, const QVector4D & v2 )

Returns true if v1 is not equal to v2; otherwise returns false. This operator uses an exact floating-point comparison.

### const QVector4D operator* ( qreal factor, const QVector4D & vector )

Returns a copy of the given vector, multiplied by the given factor.

See also QVector4D::operator*=().

### const QVector4D operator* ( const QVector4D & vector, qreal factor )

Returns a copy of the given vector, multiplied by the given factor.

See also QVector4D::operator*=().

### const QVector4D operator* ( const QVector4D & v1, const QVector4D & v2 )

Returns the vector consisting of the multiplication of the components from v1 and v2.

See also QVector4D::operator*=().

### const QVector4D operator+ ( const QVector4D & v1, const QVector4D & v2 )

Returns a QVector4D object that is the sum of the given vectors, v1 and v2; each component is added separately.

See also QVector4D::operator+=().

### const QVector4D operator- ( const QVector4D & v1, const QVector4D & v2 )

Returns a QVector4D object that is formed by subtracting v2 from v1; each component is subtracted separately.

See also QVector4D::operator-=().

### const QVector4D operator- ( const QVector4D & vector )

This is an overloaded function.

Returns a QVector4D object that is formed by changing the sign of all three components of the given vector.

Equivalent to `QVector4D(0,0,0,0) - vector`.

### const QVector4D operator/ ( const QVector4D & vector, qreal divisor )

Returns the QVector4D object formed by dividing all four components of the given vector by the given divisor.

See also QVector4D::operator/=().

### QDataStream & operator<< ( QDataStream & stream, const QVector4D & vector )

Writes the given vector to the given stream and returns a reference to the stream.

See also Serializing Qt Data Types.

### bool operator== ( const QVector4D & v1, const QVector4D & v2 )

Returns true if v1 is equal to v2; otherwise returns false. This operator uses an exact floating-point comparison.

### QDataStream & operator>> ( QDataStream & stream, QVector4D & vector )

Reads a 4D vector from the given stream into the given vector and returns a reference to the stream.

See also Serializing Qt Data Types.